188 



CA.PT. E. W. HUTTON ON THE 



crust, need not be here considered ; for I do not see that the present 

 eruption throws any new light on the question. 



The eruptions that took place on the plains were only hydro- 

 thermal in character, no great heat being developed. They followed 

 the eruption of the mountain and were, no doubt, caused by the 

 earthquakes. Their position shows that they are in some way 

 connected with the fissure on the mountain, but they cannot be 

 directly connected with it ; for, if that had been the case, they 

 would have ejected scoria like the mountain, and the explosion of 

 Eotomahana would probably have preceded that of the Okaro 

 craters. Probably molten rock was injected, as a dyke, into the 

 fissure below the surface, and the earthquakes caused the surface- 

 water to approach this dyke sufficiently close to be heated and 

 flashed into steam. These explosions, therefore, furnish evidence 

 that water cannot find its way to molten rock by means of open 

 fissures. 



Discussion. 



The President spoke of the value of the descriptive portions of 

 Mr. Martin's paper. He had enjoyed great opportunities of observa- 

 tion, and the series of photographs sent over by him was of extreme 

 interest. As regards the theoretical portion of the paper, there 

 was room for some difference of opinion. Mr. Martin had, how- 

 ever, based his theory on the study of similar structures in different 

 stages of growth. 



Referring to Capt. Hutton's paper, he said that the New-Zealand 

 geologists had shown great energy in studying the eruption. 

 I)r. Hector started at once ; some of his photographs, taken at an 

 early stage of the eruption, along with maps and specimens, were on 

 the table. Captain Hutton came somewhat later, and among his 

 discoveries were the augite-andesites which were found associated 

 with the prevailing rhyolites. He was rather disposed to regard 

 the latter as quartz-dacites. He referred to the differences of 

 opinion as to the origin of the eruption. 



Prof. Seelet regretted that Mr. Palmer, who was on the spot at the 

 time of the eruption, and whose travelling companion was killed 

 under a crushed roof, could not be present. His views were slightly 

 different from those of Capt. Hutton ; there was no eruption seen of 

 scorise and stones, nothing but grey volcanic ash and fine mud covering 

 the country. At the earliest moment possible after the eruption 

 Mr. Palmer reached Eotomahana, which was empty, but boiling 

 and spouting at the bottom. He considered that the Terraces had 

 probably been blown away, but that their sites were covered up by mud 

 and hidden by steam. The water of the lake had gone to furnish 

 some of the steam which had issued from Tarawera. There was no 

 evidence of the outburst being a true volcanic eruption. 



The President considered that Mr. Palmer might not have been 

 in the best possible position for ascertaining the effect of the erup- 

 tion In fact there were two eruptions ; of the one from the moun- 

 tain the scoriae are sent by Capt. Hutton. Those first on the spot 



